1. Field of the Invention
This invention relates to a semiconductor device produced by a tape automated bonding (TAB) method and its testing method and an apparatus to be used therefor.
2. Description of the Prior Art
A conventional semiconductor device produced by the TAB method (hereinafter called TAB semiconductor device) is illustrated in FIG. 1, which shows the state a before separation of a plurality of semiconductor elements formed on a carrier tape.
In FIG. 1, a carrier tape 21 of a synthetic resin film has a plurality of sprocket holes 22 perforated serially at the edges and along the the length thereof. The sprocket holes 22 are engaged by sprocket teeth which run the tape 21. The tape 21 also has a plurality of device-holes 23 disposed at a predetermined spaced intervals centrally in the lengthwise direction thereof. Each of the holes 23 has a semiconductor chip 24 disposed therein. On the surface of the tape 21, a wiring layer forming four sets of wiring lines 25A, 25B, 25C and 25D and four sets of external terminals 26A, 26B, 26C and 26D are patterned for each of the device holes 23. The semiconductor chip 24 is electrically connected to each set of the wiring lines 25A, 25B, 25C and 25D via inner-leads respectively provided on these wiring lines, and retained into the device-hole 23. Each set of the wiring lines 25A, 25B, 25C and 25D consists of five lines.
A conventional semiconductor element B is formed by cutting the carrier tape 21 in a unit including the device hole 23, the semiconductor chip 24 in each device hole 23, four sets of the wiring lines 25A, 25B, 25C and 25D and four sets of the external terminals 26A, 26B, 26C and 26D which are patterned around each of the device holes 23. The TAB method produces this type of semiconductor element B is produced continuously on the carrier tape 21. Namely, the carrier tape 21 having a plurality of sprocket holes 22, a plurality of device holes 23, a plurality of sets of wiring lines 25A, 25B, 25C and 25D and a plurality of sets of external terminals 26A, 26B, 26C and 26D repeats a stop and run process for successively bonding the semiconductor chip 24 to the inner-leads of each four sets of wiring lines 25A, 25B, 25C and 25D. As a result, the semiconductor chip 24 and the wiring lines 25A, 25B, 25C and 25D are electrically and mechanically connected to each other simultaneously. At the time when the bonding process is finished, a plurality of semiconductor elements B having the same structure are provided in parallel on the carrier tape 21 at predeterminedly spatially entervals along the length of the tape 21. The wiring lines 25A, 25B, 25C and 25D of each semiconductor element B are independent of those of the adjacent one, which means that the semiconductor elements B thus formed are electrically isolated from each other. The tape 21 thus having a plurality of semiconductor elements B is cut to provide separate device-hole unit.
The selection of the semiconductor elements formed on the carrier tape 21 is carried out as follows. First, the semiconductor elements B are electrically tested as a first selection process. This electrical test advantageously utilizes the continuity of devices as a feature of the TAB method in that it is carried out before the carrier tape 21 is cut, or while the tape is still joined.
Next, in order to screen initial defects, a burn-in test is carried out. This test is performed so that the carrier tape 21 is cut for separating the semiconductor elements B. The semiconductor elements B, thus separated, are individually inserted into sockets. This is based on the fact that a source voltage or input pulse for the testing purpose (hereinafter called "electric signal for testing") can not be applied simultaneously to all of the elements B because they are electrically isolated from each other.
Thereafter, the electrical test is carried out again for the semiconductor elements B thus burn-in tested as a second selection process. This test is carried out individually for each of the separated elements.
As explained above, the burn-in test is carried out conventionally after the carrier tape 21 has been cut to separating the elements. Thus, it is not possible to test the continuity of the elements as a feature of the TAB production method or, to give such an advantage that a plurality of semiconductor elements B can be continuously formed on a carrier tape. As a result, there arises such a problem that the TAB method is inferior in mass-productivity to the other methods.
This invention was made in consideration of the above-mentioned problem, and an object of this invention is to provide a TAB semiconductor device capable of improving mass-productivity by the TAB method by reducing the number of a steps to be carried out in the selection process and the other processes thereafter.
Another object of this invention is to provide a testing method of TAB semiconductor device and an apparatus to be used therefor, which is capable of improving mass-productivity by the TAB method.